Lithium (Li)

Lithium is an alkali metal with atomic number 3, in period 2 and group 1 of the periodic table. Its atomic mass is 6.94 u and its electron configuration is [He] 2s¹. Solid at 25 °C.

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Key facts

Atomic number	3
Atomic mass	6.94 u
Category	Alkali Metal
Period	2
Group	1
Block	s
Electron configuration	[He] 2s¹
Electrons per shell	2, 1
Electronegativity (Pauling)	0.98
Oxidation states	+1common in bold
State at 25 °C	Solid
Melting point	453.69 K180.54 °C
Boiling point	1615 K1341.85 °C
Density	0.535 g/cm³

Atomic properties

First ionization energy	5.392 eV
Electron affinity	59.6 kJ/mol
Atomic radius	167 pm
Covalent radius	128 pm
Van der Waals radius	182 pm
Common ions	Li⁺
Protons, neutrons, electrons	3, 4, 3

Physical and thermal properties

Molar volume	13.02 cm³/mol
Heat of fusion	3 kJ/mol
Heat of vaporization	147 kJ/mol
Specific heat	3570 J/(kg·K)
Thermal conductivity	85 W/(m·K)
Thermal expansion	4.6 × 10⁻⁵ K⁻¹
Mohs hardness	0.6
Young’s modulus	4.9 GPa
Crystal structure	Body-centered cubic
Magnetic type	Paramagnetic

Identification and history

CAS number	7439-93-2
Latin name	Lithium
Discovered by	Johan August Arfwedson · 1817
Named by	---

Natural isotopes

Isotope	Mass (u)	Abundance
⁶Li	6.015123	4.85 %
⁷Li	7.016003	95.15 %

Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.

A dash (---) means there is no reliable published measurement. The app never makes one up.

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Orbital diagram with Hund’s rule, emission spectrum, shell model, every isotope, a real photo, and comparison with any other element. Free, no ads, works offline.

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